Step 1: 3D Printing and Modeling

Why designing the fingers yourself when somebody already shared a perfect 3D model online? On Thingiverse I found a 3D model of a realistic finger. Plus, they were actually designed as hooks, so the design already contains a hole in the back of the finger. This makes it a lot easier to drill and attach the fingers later on.

I used my favorite 3D program (because it's so simple!) Tinkercad to transform five similar fingers in an actual grasping hand. The index finger and ring finger I kept the same size as the orginal 3D model. The middle finger I made slightly bigger and the pinky smaller. I changed the proportions of the thumb a bit, by making it smaller but wider.

I 3D printed the five fingers with an UP printer. It took me a couple of hours to print all of them.

Step 2: Woodworking: Lathe

An important part of the back scratcher is the wooden grip. It has to be comfortable to keep in your hand and it should be firm enough to keep the fingers in place.

You can use a pretreated round stick as grip. But I decided to make my own on the lathe. I attached a square wooden stick of a thickness of approximately 5cm x 5cm and a length of 30 cm to the lathe. After I made the stick smooth and round on the lathe with a fairly big chisel, I edited the lower part even more with a smaller chisel. This created a slightly slimmer part that makes it comfortable to hold the wooden grip in your hand.

After releasing the wooden grip from the lathe, I removed the square ends (that were attached to the lathe and therefore impossible to edit) with a saw. I ended up with a wooden grip with a diameter of 4 cm and a length of 22 cm.

Step 3: Woodworking: Drilling

I used iron wire to connect the fingers to the wooden grip. Make sure that your iron wire is strong enough, so you can give your back a firm scratch without the wire bending!

I used wire with a diameter of 3 mm, so I also used a drill bit of 3 mm. Make five holes in the wooden grip, for every finger one. Don't place them straight next to each other, but try to retain the natural line of the fingers by looking to your own hand and decide where the fingers are placed.

Don't forget to also drill a hole of the same diameter in each finger! Be careful and don't make the hole to deep.

Step 4: Attaching the Fingers

The last step is to attach all the parts (wooden handgrip, iron wire, 3D printed fingers) to each other. I used superglue to attach the fingers to the pieces wire, and the wire to the wooden grip. By bending the wire with a plier I tried to put the fingers in line to imitate a grasping hand.

When the glue is dry you can pamper yourself with a good back scratch and scare others with your creepy tool!